Zheng, QiGor, KiraSecond language (L2) speakers often experience difficulties in learning words with L2-specific phonemes due to the unfaithful lexical encoding predicted by the fuzzy lexical representations hypothesis. Currently, there is limited understanding of how allophonic variation in the first language (L1) influences L2 phonological and lexical encoding. We report how the Mandarin Chinese L1 phonemic inventory and allophonic variation subject to phonotactic constraints predict phonological encoding problems for novel L2 English words with the /v/–/w/ contrast. L1 English and L1 Chinese participants speaking two varieties of Mandarin Chinese differing as to the presence of [ʋ]–[w] allophonic variation for the /w/ phoneme participated in a vocabulary learning task. The novel L2 words with the /v/–/w/ contrast were systematically less robustly encoded than the control words on the day of training and 24 hours later. The degree of fuzziness in lexical representations was jointly predicted by L1 allophonic variation subject to phonotactic constraints and L2 phonological categorization.en-USlexical encodingnonnative listenersphonological categorizationallophoric variationmemory consolidationArticle